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What is shock?
Inadequate tissue perfusion resulting in impaired cellular metabolism
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What does shock do?
Deprives cells of essential oxygen and nutrients forcing cells to rely on anaerobic metabolism
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Shock is a result of what system?
Cardiovascular
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What alterations in the cardio system exist with shock?
Circulating blood volume, heart contractility, blood flow, vascular resistance
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Hypovolemic
Inadequate blood volume to maintain the supply of oxygen and nutrients to body tissues
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Causes of blood/fluid loss
hemorrhage, severe diarrhea or vomiting, excessive perspiration
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Excessive plasma shift can occur
with burns, peritonitis, and intestinal obstruction
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Cardiogenic shock
occurs when heart fails as a pump
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Most difficult shock to treat
cardiogenic
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Obstructive shock
Physical impairment of adequate circulating blood flow
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Causes of obstructive shock
Tension pneumothorax, pericardial tamponade, PE, abdominal distension, aortic dissection
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Cardiac tamponade
fluid collects within the pericardial sac causing compression of myocardium and resulting in reduced cardiac output and myocardial ischemia
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Superior vena cava syndrome
obstruction of the superior vena cava resulting in facial or chest edema, SOB, tachycardia and hypotension
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Vasogenic/distributive shock
improper distribution of blood due to excessive dilation of blood vessels ot decreased vascular resistance; fluid pools in dependent areas of body and is not returned to arterial circulation
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In what shock does plasma leak into interstitial compartment due to increased capillary permeability
distributive
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Types of vasogenic/distributive shock
anaphylactic, septic, neurogenic
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Most common cause of neurogenic shock
spinal cord injury above the level of the first thoracic vertebra
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Neurogenic shock
Disruption in the nervous system affects the vasomotor center in the medulla
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Signs and symptoms of neurogenic shock
bradycardia with hypotension, pooling of blood in peripheral tissues with subsequent decreased venous return and cardiac output
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Causes of neurogenic shock
injury or disease of upper spinal cord, spinal anesthesia, depression of vasomotor center from certain drugs
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Respiratory system shock effects
tissue hypoxia and anoxia, respiratory failure, ARDS
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Acid-base balance shock effects
metabolic acidosis
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Cardiovascular system shock effects
myocardial depression, widespread clotting
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Neuroendocrine system shock effects
release of epi and norepi, mineralocorticoids and ADH; decreased LOC
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Immune system shock effects
depressed immune response
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GI shock effects
decreased peristalsis, impaired liver function, death of intestinal submucosa
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Renal shock effects
reduced filtration, inadequate renal perfusion, tubular necrosis
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Compensatory stage
activation of baroreceptors in the carotid arteries and the aorta stimulate the sym NS with increased heart rate, constriction of peripheral vessels and reduced blood flow to the kidneys, lungs, muscles and GI
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Events in compensatory stage
decreased renal blood flow triggers release of renin and angiotensin II, adrenal cortex secretes aldosterone which promotes sodium retention by kidneys; falling blood pH and increasing arterial CO2 detected by chemoreceptors in carotid arteries stimulate respiratory center; increase R and depth help to eliminate excess CO2 and normalize blood pH
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Symptoms in compensatory stage
irritability, restlessness, increased P-may be thread or bounding, respirations increased rate and depth, decreased urine, cool and pale (warm and dry with septic shock), abdomen-decreased bowel sounds, increased blood glucose, thirst
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Progressive stage
systemic circulation continues to vasoconstrict to try to maintain blood flow to vital organs; decrease in peripheral blood flow leads to weak or absent pulses, blood becomes more thick, cells lack oxygen and resort to anaerobic metabolism and produce lactic acid resulting in metabolic acidosis
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Symptoms in progressive stage
listless, confusion, decreased BP, narrow pulse pressure, weak and thread pulses, tachycardia, disrhytmias, R increased, deep, crackles, T subnormal (except with septic), cold, pale clammy skin, cyanosis, dry mouth
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Irreversible/refractory stage
irreversible changes as compensatory mechanisms fail; tissue perfusion deteriorates, death is imminent cerebral ischemia due to decrease in cerebral blood flow
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Symptoms of irreversible/refractory stage
Loss OC, slow shallow R, cold clammy skin �cyanosis
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Tests that help establish type of shock
blood and urine studies, measurement of hemodynamic pressure, chest radiograph, ECG, pulse OX, ABG, urine output
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Brain cells die after how long without O2
4 minutes
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What might be ordered to decrease oxygen requirements
paralytics, sedatives, analgesics
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What fluid replacement is ordered for shock
normal saline intiallly;
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Crystalloids
provide water replacement and electrolytes
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Colloids and example
Albumin, remain in vascular system and draw fluid into the bloodstream
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Primary nursing dx for pt in shock
altered tissue perfusion-assessment includes all body systems
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Systemic Inflammatory Response Syndrome
generalized inflammation that threatens vital organs
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What conditions can lead to SIRS?
Shock, multiple transfusions, massive tissue injury, burns, pancreatitis
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Diagnosis of SIRS
T<97 or >100.4, HR>90, R>20 WBC<4000 or >12000
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Cardiogenic shock meds
dopamine, dobutamine, noepi, epi, nitro, vasopressin
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Septic shock meds
dobutamine, norepi, vasopressin
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Hypothermic suit
maintains body at 33 C, may improve neurologic recovery after cardiac arrest
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Intraaortic balloon pump
reduces preload with cardiogenic shock, heart pumps more efficiently, increases cardiac output
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External counterpulsation device
pump applies pressure during diastole and relieves during systole, reduces preload
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Ventricular assist devices
decreases myocardial workload and O2 demand; supports circulation until heart recovers or is replaced
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Extracorporeal membrane oxygenation
blood is removed from inferior VC, oxygenated, and returned via femoral artery; used for short term stabilization
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All types of shock require fluid replacement except
cardiogenic
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The basic cause of vasogenic shock is
dilation of blood vessels
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What would explain massive edema in anaphylactic shock
increased capillary permeability
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When patients lose plasma, what fluid is most appropriate for restoring blood volume?
Crystalloid fluids
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Majority of cardiogenic shock are caused by
MI
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Most common neurogenic shock
spinal cord injury
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What is most likely to cause extravasation
vasopressors
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First priority in treatment of shock from car accident
get blood to brain
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